The overall goal of the grant is to understand the way that vision functions in the context of ordinary behavior. To do this we must understand the transition between the low level perceptual machinery and the ongoing sensory-motor behavior, a transition that spans a time scale of a few hundred milliseconds to that of several seconds. In the context of ongoing behavior, vision is highly selective. The information extracted from the image during a fixation is fragmentary, and driven by the immediate task demands: in different fixations on a given location, different information may be acquired, although the retinal image is identical in each case. This selectivity leads to a very different understanding of vision, not as performing a general purpose set of transformations, but as dynamic process that extracts specific, limited information from the image for the immediate task. Our research goal is to characterize the nature and extent of this selectivity. In addition, the experiments lay the foundation for a rigorous understanding of how elementary visual and motor operations are composed into more complex ongoing behavior. Thus the grant develops new paradigms to validate this functional approach to vision. The fragmentary nature of millisecond visual representation presents a problem for coordinating larger behaviors. Visual representations must be sufficiently extensive to preserve the continuity of visual experience and mediate coordinated movements. Thus the experiments focus on what information is extracted and retained across fixations, whether it is used to guide subsequent eye movements, and how different kinds of information are composed to make up larger behavioral units. Specific aims are (I) Does an implicit memory representation for scene structure provide the representational substrate for "marking" salient locations in a scene and for selecting the target for saccade? (2) Do observers use the same representational mechanisms to access information in a more spatially realistic visual environment where the scale of the movements is different? Does coding by remembered location involves loss of information about object features? (3)Can a complex task like driving be broken down into the sequential application of sub-component tasks with specific control variables, and how are these sub-components integrated? The goal is to understand the balance between task-directed, top-down visual processing, and bottom up or stimulus-driven visual processes. Independent of issues about visual representations, we need to look at performance in the context of ordinary tasks because we know very little about how vision is used in ordinary circumstances. This information shapes the questions we ask, and also is directly applicable to a number of practical and clinical issues, such as the impact of particular neural deficits on everyday visually guided behavior.